Runs bad under a load

Hello all
I have a cub with a 22hp kohler and 60" deck. It ran and stoped ran and stoped so I redid the fuel lines from tank to pump. Fixed that. Now a tube under the air filter has a fuel and oil mix coming out and chocking down the motor while under a load mowing or a hard pull. Blows lots of smoke out the muffler fouls the plugs. Runs ok when not under a load.. Blow-by I'm guessing?? What is the fix?? Please
Thanks John